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Ablation of ventricular tachycardia (VT) is a procedure that is becoming increasingly more widespread in clinical practice.1 It is estimated that 12% to 17% of cases of VT are of myocardial and subepicardial origin, which is a more common substrate in nonischemic heart disease.2 Rhythmia (Boston Scientific; Marlborough, Massachusetts, United States) is a new nonfluoroscopic navigation system able to generate high-density maps combining a steerable 64-electrode catheter (IntellaMap Orion; Boston Scientific) with software able to automatically capture the recorded electrograms. Given the novelty of the system, experience with this catheter for epicardial mapping is very limited,3 and no information has been published on the outcomes and complications of VT ablation guided by the Rhythmia system.

We present the case of a 56-year-old physician who was an endurance sports enthusiast. He started to experience frequent episodes of palpitations, generally triggered by exercise, and accompanied by nausea. On exercise testing, regular sustained broad QRS tachycardia was induced with right bundle branch block and left superior axis morphology. In the 24-hour Holter recording, 80 episodes of the same tachycardia were detected. The results of both echocardiography and coronary angiography were normal, and diagnosis of VT was confirmed in an electrophysiology study. On magnetic resonance imaging, a 30×7-mm area of gadolinium enhancement was observed between the myocardium and subepicardium of the inferior wall of the left ventricle.